Question: how can you tell if a bird is healthy or unhealthy

Renata Medeiros answered on 18 Jun 2013:

Interesting question! It’s usually based on their weight. A skinny bird is usually a sign of being unhealthy. So it is important that we know for each species what is a good weight. And sometimes this can be tricky, in my research with storm petrels we realised that in years when the birds were heavier it actually meant they were struggling to find food and so ate a lot whenever they could because they weren’t sure when to find food again. However, being too heavy makes flight more difficult so these birds were actually healthier in years when they were a bit lighter. Still, if they got too skinny that would also be a sign of being unhealthy and it is actually happening in the last few years.